Documentation of the sidescan sonar data format is summarized here. The sidescan data are presented in two different ways to make them available to a broader community of users. They are presented in an unmerged form and as netCDF files.
In the unmerged form, the header information and the imagery are in separate files which both have the same prefix but different suffixes. The header information is contained in files with a hdr suffix (e.g. t1f01.hdr). These are ASCII files with the following fields:
Field 1: Line number Field 2: Year - two digits Field 3: Month Field 4: Day Field 5: Hour Field 6: Minute Field 7: Second Field 8: Latitude in decimal degrees Field 9: Longitude in decimal degrees Field 10: Heading - this is 0 if heading was not logged Field 11: Uncorrected depth in meters Field 12: Corrected depth in meters - corrected for variations of the speed of sound in water.
The associated sidescan image files that go with the header files have a suffix of ".img" (ie. t1f01.img). These files are 8-bit binary raw images. There is no tagged information identifying their size, but in the "unmerged" directory there is an ASCII file titled "filesize.txt" that summarizes the number of lines (NL) and samples (NS) in each file along with start and end time of each file.
The second data form is the netCDF file form that is compatible with the USGS WHIPS sidescan sonar processing software (Paskevich, 1992). A description of the NetCDF format, as implemented within the WHIPS software, is included here.